So MakerGear tech support were super helpful as usual, and I was super stupid. Because I had the extruder all apart and was only focused on the extruder motor gear, I forgot the hotend has to be heated up above 170C before the firmware will let the extruder motor turn – doh! All working good now. Thanx to everyone that helped.

I now have a UK based spare RAMBo available to sell if any other UK M2 users needs one for much cheaper shipping.